Honeyboy has actually proved to be quite sneaky in the way they redressed the interior of the station… One scene featured Rico (Erik Estrada) opening the door to let his PR agent (Morgan Fairchild) and a photographer into the apartment shared with the rest of his family, and visible through the door was the third floor landing of the staircase.
For a while I was wondering if they’d filmed the sequence on the third floor, with false walls… And while false walls were used in the shot, it was filmed in the second floor assembly room and the dormitory, with the aid of a photographic backdrop of the third floor staircase landing. 
The SoCal Ghostbusters’ 2010 tour of Fire Station №23 once again proved invaluable in trying to work things out, so it seems only right to post Vincent Nordone’s videos here for future reference:
https://www.youtube.com/watch?v=WOUUJh_wl7Q
https://www.youtube.com/watch?v=GlfNJ0CQzGE
https://www.youtube.com/watch?v=BAP7E9R5hcY